An image of a set of scales. On the right side, there is a small version of Granger standing, being weighed. The left side of the scales is filled with small versions of other characters: Voldemort, Dumbledore, McGonagall, the Dursleys, Zabini, Crabbe, and Goyle. A hand reaches from above and pushes down Granger's side, so it appears that Granger is weighed heavier than all the others put together.

The illustration was inspired by the Ancient Egyptian myth. According to the myth, in the afterlife, your heart/soul is weighed against a feather. If it's heavier (meaning more evil) than the feather, then it will be devoured by a monster.

Incidentally, I've known what this image will be for a long time. For the earlier chapters, I've invented most of the title-page visual metaphors on the same days I drew them, but for this one and the next one, I've known since before I drew the first page.